Coated clumping litter

ABSTRACT

A clumping animal litter is disclosed which includes non-swelling particles and a swelling agent coated on the non-swelling particles. In one embodiment, the non-swelling particles are manufactured by agglomerating clay fines.

BACKGROUND OF THE INVENTION

This invention relates generally to absorbent materials, and morespecifically to, various litter compositions used for the control andremoval of animal waste.

Known litter compositions are fabricated primarily from one of fourmaterials: clay; vegetable matter such as grass, hay or alfalfa; woodchips, shavings or sawdust; and paper, such as shredded, flaked orpelletized paper. Known clay litters are prone to produce dust, andtracking out by the animal. Further, production of such clay littersresults in a large quantity of dust being produced, sometimes referredto as clay fines. Clay fines present a problem to the littermanufacturers since the fines are a waste product and require disposal.In addition such clay products are not biodegradable.

Sodium bentonite clay is one known material used in the production oflitters and is known for its excellent absorption and clumpingqualities, as well as for odor retention. However, sodium bentonite isrelatively expensive compared to other litter components. Therefore,attempts have been made to reduce the amount of sodium bentonite inclumping litters, for example, mixing pellets of non-absorbing clayswith pellets of sodium bentonite clay in varying ratios. However, inthese known litters, the properties which are most desirable in thesodium bentonite have been underutilized as most of the clumping andbinding qualities of sodium bentonite occur at or near the surface ofthe clay.

SUMMARY OF THE INVENTION

In one aspect, an animal litter is disclosed which comprisesnon-swelling particles and a swelling agent coated on the non-swellingparticles.

In another aspect, an absorbent material is disclosed which comprisesclay particles in a size range of −10 to +50 mesh and a coating for theparticles which comprises a bentonite powder.

In still another aspect, a clumping animal litter is disclosed whichcomprises clay particles in a size range of about −10 to +50 mesh whichare agglomerated from clay fines of about −50 mesh size. A coatingsurrounds the particles.

In a further aspect, a method for manufacturing a clumping animal litteris disclosed which comprises agglomerating clay fines into particles andcoating the particles with a powder.

In yet another aspect, a clumping animal litter is disclosed whichcomprises clay particles in a size range of about −10 to +50 mesh insize and bentonite powder of about 200 mesh size. The powder is appliedas a coating to the particles in an amount of about 20% to about 40% byweight.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross sectional view of a particle of coated clumpinglitter.

FIG. 2 is a clumping analysis of several samples of coated clumpinglitter.

FIG. 3 shows a screen analysis, a bulk density, and a moisture contentfor each sample analyzed in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, absorbent particles 10 include clay finesagglomerated into clay particles 12, which are coated with a powder 14.In one embodiment, absorbent particles 10 are utilized in an animallitter. In alternative embodiments, the animal litter includes cat, dog,hamster and livestock litter. The clay fines used in the agglomerationprocess are about −50 mesh in size and are sometimes referred to as aclay seed base or a seed material. In an exemplary embodiment, clayparticles 12 range in size from about −10 mesh to about +50 mesh, basedon standard U.S. mesh.

In an exemplary embodiment, the clay fines are agglomerated using a pinmixer. A powder 14 is applied to particles 12 to form a coating. Powder14 is the active ingredient of the litter. Exemplary coating powdersinclude at least one of a sodium bentonite powder and a bentonite/guargum blended powder. However, the powder coatings may be augmented witheither or both of an odor control agent and an anti-microbial agent.Particle 10 is spherical in shape, the shape shown is by way of exampleonly as it is contemplated that a host of shapes and sizes of coatedparticles can be produced by the embodiments and processes describedherein.

One specific embodiment includes recovery of waste fines which includeCalcium-Montmorillonite. The Calcium-Montmorillonite fines areagglomerated in a pin mixer using water as a binder. The agglomeratedfines have a moisture content of about 20% to about 40%. In anotherembodiment, the fines have a moisture content of about 28% to about 34%.The agglomerated fines are then coated with a bentonite powder of about200 mesh using a centrifugal coater or a rotary coater/dryer system.

In one embodiment, the clay fines are fed into a pin mixer using a screwextruder. Moisture (water) is added to the fines to act as a binder, inone embodiment about 28%, while in the extruder. The fines and themoisture result in a cake like substance as it enters the pin mixer. Apin mixer includes a shaft with a series of pins which breaks up thecake and results in the formation of small, spherically shaped particleswhich are separated from the cake-like batch using shaker screens. Aspreviously described, in one embodiment, the clay fines are about −50mesh in size and after addition of the moisture and the pin mixingprocess, resulting in particles 12 of between about −10 mesh and +50mesh in size. Other methods are contemplated which include using bindersof guar gum and water or starch and water.

Another embodiment utilizes a blend of clay fines and bentonite fineswith water as a binder to produce particles 12 through the pin mixingprocess. Still another embodiment utilizes sodium bentonite fines withwater as a binder to produce particles 12 of between about −10 mesh and+50 mesh in size through the pin mixing process. The agglomerated fines,including the clay and bentonite embodiment, or the bentoniteembodiment, are then coated with a bentonite powder of about 200 meshusing a centrifugal coater or a rotary coater/dryer system for improvedclumping capability.

In alternative embodiments, methods for coating an outer surface of clayparticles 12 with powder 14 include utilization of at least one of afluidized bed dryer, a semi-continuous centrifugal coater or a rotarycoating and drying system. In the rotary system, clay particles 12 andpowder 14 are tumbled in a drum to mix for about 60 seconds. The litteris then removed from the drum and the drum is heated to about 300° toabout 400° Fahrenheit and the litter is returned to the drum and drieduntil about an 8% moisture content is obtained.

The resulting coated litter is typically in the −10 to +50 mesh sizerange, with a moisture content from about 15% to about 5%, preferablywith a moisture content of about 8%. In one embodiment, the bentonitecoating is about 20% to about 40% by weight of a coated particle. In analternative embodiment, the bentonite coating is about 25% to about 35%by weight of a coated particle. In a further alternative embodiment, thebentonite coating is about 30% by weight of a coated particle.

In alternative method for producing the litter, the agglomerated finesare placed in a fluidized bed and bentonite coating is sprayed in a lowconcentration solution.

FIGS. 2 and 3 are an analysis of several samples of coated clumpinglitter which includes 70% by weight particles produced from fines asdescribed above and 30% by weight 200 mesh bentonite coating. FIG. 2illustrates clumping weight and clumping strength for severalrepresentative samples and is charted based upon wetting, for example,15 minutes after wetting with a saline solution, and for 15 minutes, onehour, and 24 hours after being wetted with a standard urine sample. FIG.3 shows a screen analysis, a bulk density, and a moisture content foreach sample analyzed in FIG. 2. The screen analysis indicates a weightand a percentage for each sample that passed through standard meshscreens, for example, 8, 12, 14, 20, 40, and 50 mesh screens.

The litter resulting from the compositions and methods described abovehas superior clumping properties as the active clumping agent is kept onthe surface of the particles, where the clumping bonds are formed. inaddition, the litter has a dust content which is lower than knownclumping litters, resulting in less tracking, as the coating processesdescribed above result in a shell being formed around the agglomeratedparticles. Further, the litter is easier to remove from litter boxesthan known clumping litters as the litter described herein is lesslikely to attach to litter boxes.

In the above described embodiments, coating with bentonite provides alitter which includes the clumping and absorption qualities of a litterwhich is composed solely of sodium bentonite. However, due to thecoating process, the amount by weight of sodium bentonite is reducedover known clumping litters, resulting in more efficient use of thesodium bentonite while providing a production cost savings over thoselitters with higher percentage amounts of sodium bentonite. In addition,the coated litter produced provides a lighter weight product and has aunique, homogeneous appearance that appeals to consumers. Further, theagglomeration process results in a utilization of clay product fines,which heretofore have been considered waste products, and since clay isnot biodegradable, clay fines have traditionally required space fordisposal.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

1-51. (canceled)
 52. A method for manufacturing an animal littercomposition, the method comprising: agglomerating clay fines andbentonite fines to form an absorbent particle; and coating the absorbentparticle with a swelling agent.
 53. The method of claim 52 wherein theswelling agent comprises bentonite powder.
 54. The method of claim 52wherein the absorbent particle has an outer surface and the swellingagent is coated on the outer surface of the absorbent particle.
 55. Themethod of claim 52 wherein the clay fines and the bentonite fines areagglomerated in a pin mixer.
 56. The method of claim 52 wherein coatingthe absorbent particle comprises coating the absorbent particle with abentonite powder and a guar gum powder blend.
 57. The method of claim 52wherein coating the absorbent particle comprises coating the absorbentparticle using at least one of a fluidized bed dryer, a semi-continuouscentrifugal coater, and a rotary coating and drying system.
 58. Themethod of claim 52 wherein the absorbent particle has a size in therange of −10 to +50 mesh.
 59. The method of claim 52 further comprisingdrying the coated particle.
 60. The method of claim 59 wherein dryingthe coated particle comprises drying the coated particle to a moisturecontent from about 5% to about 15%.
 61. The method of claim 52 whereincoating the absorbent particle comprises applying a swelling agent in anamount of about 20% to about 40% by weight of a coated particle.
 62. Themethod of claim 61 wherein coating the absorbent particle comprisesapplying a swelling agent in an amount of about 25% to about 35% byweight of a coated particle.
 63. The method of claim 61 wherein theswelling agent comprises bentonite powder.